Novel Aortic Root Measurement Technique Using the Laplace Diameter for Identifying Patients at Risk for Type A Dissection.

Background: The Laplace law is commonly applied to calculate aortic wall stress by using the luminal pressure and the aortic diameter. Wall stress bears on the likelihood of aortic dissection in dilated aortas. However, the Laplace law applies only to circles and cylinders. It is not applicable for the aortic root, which can be more closely described as a cloverleaf shape, rather than a circle. We have recently developed a mathematically based measuring technique specifically for the aortic root. This Laplace diameter provides an appropriate means to measure a "diameter" for the cloverleaf shape of the aortic root. Methods: In this study, we assessed the predictive ability of the Laplace diameter vs the standard sinus-to-commissure measurement in 33 patients who underwent predissection computed tomographic scans for unrelated reasons in close temporal proximity to their acute aortic event. We analyzed 14 chest computed tomographic scans of 33 patients who received predissection scans for unrelated reasons. Results: We observed a 16.1% increase in the mean root diameter using the Laplace diameter. We found that 21.4% of the analyzed predissection scans could have resulted in detection and prevention of the aortic dissection through surgery if the Laplace diameter had been applied. Conclusions: We validated the novel method of the Laplace diameter clinically in determining the aortic root diameter and detecting the risk of aortic dissection.